The invention herein resides in the art of dynamoelectric machines and, more particularly, in the art of bypass motor/fan assemblies. Particularly, the invention relates to a bypass motor assembly in which the working air is provided with a laminar outward and downward exhaust flow path, greatly increasing the efficiency of the assembly. An air intake seal is also provided to improve the assembly""s efficiency.
Presently, many pieces of cleaning equipment are subjected to water or moisture. Particularly, wet/dry vacuum cleaners such as those known as utility vacs and carpet extractors operate in an environment in which the debris which is extracted from the surface being cleaned is laden in a mixture of air and water. In order to prevent the moisture laden air from entering the vacuum generating motor, bypass motors are typically used in these operations. As is known to those skilled in the art, a bypass motor/fan assembly is one in which the working air, generated by a working air fan, never passes through the motor, but is totally isolated from the motor. The motor itself may have a separate motor cooling air fan which draws cooling air over the motor armature and field. Accordingly, the working air and the motor cooling air take totally separate paths, and do not mixxe2x80x94except possibly in an exhaust area. While both the motor cooling fan and the working fan operate on the same shaft, in a bypass motor the chambers for the working air and motor cooling air are separate and distinct from each other such that moisture laden air never enters the motor.
In the past, bypass motors have typically positioned a working air fan at an end of the motor/fan shaft, with the fan rotating within a fan shell, which is sometimes called a shroud. The shell defines a chamber within which the fan operates. An end of the fan shell is provided with an air intake, with the circumference or periphery of the shell being defined by a plurality of spaced apart exhaust apertures. The intake aperture communicates with a vacuum chamber in the cleaning device, while the exhaust ports communicate with the ambient. Typically, the fan shell simply defines a chamber in which the fan rotates and, accordingly, that chamber becomes pressurized such that the air therein eventually finds its way to an exhaust port. However, with this type of a structure, the fan operation is quite inefficient.
Those skilled in the art will appreciate that previously known bypass motors are highly inefficient. The pressurization of the fan chamber and the indirect exhausting of the air therefrom gives rise to inherent air flow inefficiencies. Accordingly, there is a need in the art for a highly efficient and quiet bypass motor for use in motor/fan applications involving moisture laden air.
One attempt at improving bypass motors is disclosed in the U.S. patent application Ser. No. 09/072,035, entitled xe2x80x9cBypass Motor/Fan Assembly Having Separate Working Air Passages,xe2x80x9d which is assigned to the Assignee of the present invention and incorporated herein by reference. This application discloses a fan end bracket, positioned below a bottom surface of the working air fan in such a way that the working air is moved out and down through separate and distinct exhaust apertures that are aligned with exhaust ports of the fan shell or shroud. Although this is an improvement over previously known bypass motor/fan assemblies, turbulence still occurs. Accordingly, there is still a need in the art for improvement in the efficiency of a bypass motor for use in motor/fan applications.
In light of the foregoing, it is a first aspect of the present invention to present a bypass motor/fan assembly in which the working air is exhausted through gradually expanding vanes of uniform cross-section, thereby increasing efficiency.
Another aspect of the present invention is the provision of a bypass motor/fan assembly in which the working air fan is maintained in a fan cavity formed by the vanes of a fan end bracket and in which the plurality of vanes are positioned in close proximity to the exhaust ports of the working air fan.
Yet another aspect of the present invention is to provide a bypass motor/fan assembly, as set forth above, in which a channel formed between the vanes gradually expands which, in turn, places exhaust air in an annular gathering chamber and then out through the exhaust apertures of a fan shroud.
A further aspect of the present invention is to provide a bypass motor/fan assembly, wherein the fan shroud provides a logarithmic-shaped discharge area that gradually increases in size until tangentially exhausted.
Still another aspect of the present invention is to provide a bypass motor/fan assembly, as set forth above, in which an interior surface of the fan shroud contacts at least a portion of each vane""s top edge.
Still yet another aspect of the present invention is to provide a bypass motor/fan assembly, as set forth above, in which an air intake seal is disposed between the shroud and the working air fan to directly transition inflowing air into the working air fan.
The foregoing and other aspects of the present invention, which shall become apparent as the detailed description proceeds, are achieved by a bypass motor assembly, comprising a motor having a rotatable shaft, a working air fan secured to the rotatable shaft, a shroud having an intake eyelet and at least one exhaust aperture, an end bracket having a shaft hole through which the shaft extends, the end bracket and the shroud partially enclosing the working air fan, wherein rotation of the working air fan draws air in through the intake eyelet and exhausts the air through at least one exhaust aperture, and the end bracket having a plurality of vanes that form a fan chamber that receives the working air fan such that air expelled by the working air fan is re-directed by the vanes toward at least one exhaust aperture.
Other aspects of the present invention are attained by a bracket for a bypass motor assembly which includes a tapered working fan rotated by a motor shaft, wherein the tapered working fan is partially enclosed between a shroud and the bracket, the bracket comprising a base having a periphery, a shoulder extending from the periphery, and a plurality of vanes extending from the shoulder, the plurality of vanes facilitating movement of air expelled by the tapered working fan out the shroud.
Still another object of the present invention is attained by a motorized fan assembly, comprising an end bracket with a rotatable shaft therethrough, a shroud having an intake eyelet and a plurality of exhaust apertures, the shroud enclosing the end bracket, a fan connected to the rotatable shaft, and rotatably received between the end bracket and the shroud, and an air intake seal disposed between the shroud and the fan.
These and other objects of the present invention, as well as the advantages thereof over existing prior art forms, which will become apparent from the description to follow, are accomplished by the improvements hereinafter described and claimed.